The overall objective of this research is the understanding of mechanisms and conditions of occurrence of interactions between peroxidizing lipids and other food constituents, notably proteins, amino acids and vitamins. The research is concentrated on interactions occurring in systems simulating dehydrated, intermediate moisture and frozen foods, but the work had implications for other biological systems. In previous work we have shown the presence of protein-centered free radicals following reactions between lipid peroxides and proteins. Lysozyme reacted with peroxidizing lipids showed formation of polymers, apparently due to a radical polymerization mechanism. Work proposed for next year includes: (a) Determination of enzymatic activity of different lysozyme polymers produced by reactions with lipids. (b) Characterization of the role of state of lipid dispersion in dehydrated systems in affecting oxidative reactions involving proteins. (c) Further characterization of changes in amino acid residues after reactions with lipid peroxides.